Size-dependent assembly of ligated gold nanocrystals in two dimensions

Abstract

Brownian dynamics (BD) simulation based on a coarse-grained model is performed to study the assembly of dodecanethiol-ligated Au nanocrystals (NCs) at a toluene-air interface. With increasing diameter from 3 nm to 9 nm, the NCs are found to form three different phases-a dispersed phase without aggregation, a mixture of dispersed NCs and rounded clusters, and a compactly packed solid phase of the fractal structure. Such size dependence of the assembled phase is attributed to the variation in the well depth [Formula: see text] of the interaction potential between NCs, and the value of [Formula: see text] for 6 nm NCs turns out to be most suitable to form monolayers with hexagonal packing. The result is of universal importance for assembling complete monolayers, because the valley of the interaction potential can be well tailored by properly choosing the NC size, ligand length and solvent.

Structural Properties of Nanometer‐Sized Gold Nanoparticles on a Silicon Substrate

“…[7] Au clusters are among the most extensively explored transition-metal clusters in view of their potential applications in microelectronics, nanotechnology, and biomedicine. [4,[8][9][10] Au NPs of the socalled "magic" sizes, which can be viewed as stacks of regular atomic lattice planes, have been predicted to be particularly stable, although Petkov et al [3] have pointed out that one should not overlook the possibility of losing order, and Au has indeed been shown to display a tendency to form amorphous structures. [11] Notably, asymmetric NPs, which usually possess energies similar to those of their symmetric, closed-shell counterparts, add to the rich energy landscape of NPs.…”